hi mate take the bung out, the one in the top of your thermostat housing .The bung is black plastic. Once removed fill the system up from your header tank and thermostat housing bung hole until water is pumping out not just spitting at you ! put the bung back in and away you go !
better still - change the plastic bungs in the thermostat and radiator for household radiator bleed valves (the same thread) for about £2 each, then yu can bleed the system in use and even when hot
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